Abstract Deep saline aquifers (DSAs) represent the Earth's largest CO2 storage resource, constituting approximately 96% of the over 14000 GtCO2 global aggregated storage resource (OGCI, 2024). Capturing this vast potential for sustainable CO2 storage in DSAs demands robust modeling frameworks that fully couple advective multiphase flow, reactive transport of CO2 in the subsurface, capillary and relative permeability hysteresis, CO2–brine mutual solubility, and poromechanical deformation. However, due to high computational costs and limited research scope, most of the CO2 storage studies in literature have integrated only a subset of the fully resolved physical, chemical and operational controls that impact field-scale CO2 storage performance in DSAs, often relying on simplistic assumptions and approximations that may undermine their applicability. In this study, we present a full-physics simulation framework for CO2 storage in DSAs integrating a detailed geological model that captures reservoir geometry, seals, and structural features. Our comprehensive framework also includes dynamic multiphase flow characteristics with relative permeability and capillary-pressure hysteresis, and advanced thermodynamics with equation- of-state formulations for supercritical CO2–brine system. Importantly, we also consider reactive transport modules to capture mineral dissolution, water vaporization, salt precipitation, and mineral trapping in our framework. A 2-way coupled geomechanics for solving injection-induced poroelastic stress-strain relationships and its associated porosity changes, as well as caprock integrity and uplift/subsidence have been also incorporated. Furthermore, near-wellbore processes including brine dry-out and salting-out have been carefully accommodated in our novel framework. Notably, we adopt a high-resolution numerical discretization scheme with local grid refinement feature in order to optimize the accuracy-efficiency trade-off, making our simulation framework a fully resolved, yet applicable solution for field-scale analyses. The base-case simulation confirmed that sustained CO2 injection is feasible under the operational bottom hole pressure (BHP) constraints, with three injectors achieving stable target rates over the 30-year injection period. Post-injection migration was governed by buoyant rise and capillary hysteresis, yielding a plume that remained contained within the primary aquifer and progressively thinned and spread up-dip. After 500 years, CO2 partitioning was dominated by residual trapping (66%), with smaller contributions from dissolution (11.5%), free phase CO2 (22%), and negligible mineralization (∼0.05%). The model sensitivity to various physical, chemical, and operational controls was investigated. Thin aquifers and low-porosity cases experienced earlier injectivity loss and higher caprock failure potential, while deeper and thicker aquifers sustained higher injection volumes but retained larger proportions of mobile CO2. Salinity and dip angle strongly influenced plume footprint and trapping partitioning, whereas ambient hydrodynamic flows displaced the plume footprint laterally, shifting the monitoring area of review. Collectively, these results emphasize the importance of full-physics coupling in predictive storage modelling, as simplified approaches risk misrepresenting the balance of trapping mechanisms, plume migration behavior, and long-term geomechanical risks.
Osemoahu et al. (Mon,) studied this question.